Couple Questions im stuck on.

1) Let F: X -> Y be a function. Justify your answer to each question below by giving either a proof or a counter example.

a) Does f(A - B) = f(A) - f(B), for all A,B subsets of X?

b) Does f(inverse)(C - D) = f(inverse)(C) - f(inverse)(D), for all C,D subset of Y.

Just a not, when I say A - B that is the difference between the sets.

I think I know somewhat how to approach this> I believe I have to prove through the use of set images and that such, but I am stuck. Any help would be great.